We previously demonstrated, in luteinizing hormone (LH)-deficient macaques, that follicular growth and maturation occurred with exogenous (recombinant human) follicle stimulating hormone (r-hFSH) administration alone and that the oocytes recovered fertilized at a notably higher rate than their counterparts from animals receiving both r-hFSH and r-hLH (Zelinski-Wooten et al., 1995). Here, the developmental potential of embryos produced from animals treated with r-hFSH alone or in combination with r-hLH was evaluated. Embryos (n=127) were cryopreserved, thawed and either co-cultured on buffalo rat liver cells until the hatched blastocyst stage or transferred to synchronized recipients. Although embryos from each treatment group demonstrated a similar ability to develop to hatched blastocysts with a definitive inner cell mass, a significant difference was seen in cryosurvival (56 vs 78%) and in developmental rate to the hatched blastocyst (12 vs 10 days) between embryos from the r-hFSH alone and the combination group, respectively. Pregnancies resulted following oviductal embryo transfers in both groups with corpus luteum rescue occurring on days 12-16 of the luteal phase. In summary, r-hFH alone during the preovulatory interval is adequate for the gametogenic events required to produce embryos that develop either in vitro or in vivo; however, exposure to r-hLH may improve embryo viability and the rate of development.